init Run Log Standardization

Overview

Introduction

Basic functions of a log include recording key nodes and troubleshooting faults during the init startup process.

Logs help troubleshoot faults, check the startup duration of each subsystem, command execution duration, and more.
Log tags (including param, uevent, and module) for different modules can be viewed.
Logs can be printed for key phases, for example, the startup of the first phase, a required partition and its device node, uevent creation, service startup, and more.
Logs can be printed according to the specified log level. Currently, the following log levels are available: INIT_DEBUG, INIT_INFO, INIT_WARN, INIT_ERROR, and INIT_FATAL.

Basic Concepts

The implementation of init logs varies according to the OpenHarmony version.

OpenHarmony standard: The init log is implemented via dmesg log of the Linux kernel.
OpenHarmony LiteOS L1: The init log is implemented via hilog.
OpenHarmony LiteOS L0: The init log is implemented via printf.

Constraints

None

How to Develop

Use Cases

init logs are mainly used to start modules (like param, ueventd, and module) during init startup, and are used in the open API begetutils.

Available APIs

Table 1 Log APIs

API	Format and Example	Description
INIT_LOGV	INIT_LOGV("Add %s to job %s", service->name, jobName);	Prints the log of the DEBUG level.
INIT_LOGI	INIT_LOGI("Start init first stage.");	Prints the log of the INFO level.
INIT_LOGW	INIT_LOGW("initialize signal handler failed");	Prints the log of the WARN level.
INIT_LOGE	INIT_LOGE("Failed to format other opt");	Prints the log of the ERROR level.
INIT_LOGF	INIT_LOGF("Failed to init system");	Prints the log of the FATAL level.
INIT_ERROR_CHECK	INIT_ERROR_CHECK(ctx != NULL, return NULL, "Failed to get cmd args ");	Prints a log and executes return NULL when ctx != NULL is not true.
INIT_INFO_CHECK	INIT_INFO_CHECK(sockopt != NULL, return SERVICE_FAILURE, "Failed to malloc for service %s", service->name);	Prints a log and executes return SERVICE_FAILURE when sockopt != NULL is not true.
INIT_WARNING_CHECK	INIT_WARNING_CHECK(argsCount <= SPACES_CNT_IN_CMD_MAX, argsCount = SPACES_CNT_IN_CMD_MAX, "Too much arguments for command, max number is %d", SPACES_CNT_IN_CMD_MAX);	Prints a log and executes argsCount = SPACES_CNT_IN_CMD_MAX when argsCount <= SPACES_CNT_IN_CMD_MAX is not true.
INIT_CHECK	INIT_CHECK(arg != NULL, return NULL);	Executes return NULL when arg != NULL is not true.
INIT_CHECK_RETURN_VALUE	INIT_CHECK_RETURN_VALUE(errno == 0, -1);	Executes return -1 when errno == 0 is not true.
INIT_CHECK_ONLY_RETURN	INIT_CHECK_ONLY_RETURN(cmd != NULL);	Executes return when cmd != NULL is not true.
INIT_CHECK_ONLY_ELOG	INIT_CHECK_ONLY_ELOG(execv(argv[0], argv) == 0, "execv %s failed! err %d.", argv[0], errno);	Prints only log "execv %s failed! err %d." when execv(argv[0], argv) == 0 is not true.

Development Example

Call an API to print the log.

For example, call INIT_LOGI("Start init first stage.") in //base/startup/init/services/init/standard/init.c to print the log.

void SystemPrepare(void)
{
   MountBasicFs();
   CreateDeviceNode();
   LogInit();
   // Make sure init logs are always printed to /dev/kmsg.
   EnableDevKmsg();
   INIT_LOGI("Start init first stage.");
   // Only the OpenHarmony standard system supports
   // two stages of init.
   // In updater mode, only one stage of init is supported.
   if (InUpdaterMode() == 0) {
       StartInitSecondStage();
   }
}

Run dmesg to check the printed log Start init first stage.

Set the log level by using the begetctl command.

The command is begetctl setloglevel level, where level indicates one of the following log levels: 0 (INIT_DEBUG), 1 (INIT_INFO), 2 (INIT_WARN), 3 (INIT_ERROR), and 4 (INIT_FATAL).

After the setting is complete, the level set via g_logLevel of init takes effect immediately, and log APIs can print logs only when their log levels are higher than or equal to this level. For example, begetctl setloglevel 3 sets the log level to INIT_ERROR. In this case, only INIT_LOGE and INIT_LOGF will print logs.

After the system is restarted, the configured log level will take effect after the load_persist_params command in the init.cfg file is executed.